Fatigue Flexural Behavior of Reinforced Concrete Beams

External post-tensioning is an attractive technique for strengthening reinforced concrete structures because of its ability to actively control stresses and deflections, speed of installation, minimum interruption for the existing structure, and ease of inspection under service conditions. However, external prestressing implies exposing the tendons to the environment outside the concrete section, which may lead to corrosion in steel tendons. Therefore, the interest in using Carbon fiber reinforced polymer (CFRP) tendons, which are corrosion resistant, has increased. The present work investigated, experimentally and theoretically, the flexural performance of reinforced concrete beams strengthened with externally post-tensioned Carbon FRP (CFRP) tendons, under fatigue loading. Fatigue experiments on five beams (160x280x3500 mm) were undertaken. Midspan -deflection, concrete, steel bar and CFRP tendons strain and cracks width were measured at different numbers of load cycles and varying fatigue loading levels during the test. Test parameters included the tendon profile and the load levels applied to the beam during the fatigue life (27%, 35%, 0.43% and 48% of their ultimate load).